Spectrum sharing technology is steadily gaining both attention and momentum within various regulatory bodies, standards groups such as ETSI and 3GPP and industry for a such as the Wireless Innovation Forum. Spectrum sharing technology is expected to be the leverage for regulators to increase 5th Generation (5G) mobile applications capacity.
Sharing frameworks are established under the responsibility of the administration of a mobile network and need to at least identify incumbents and spectra to be made available under comprises (as a minimum) the identification of the incumbent the spectrum to be made available for sharing, and the corresponding conditions for shared spectrum access by both incumbent(s) and sub-licensee. Two major sharing framework approaches are currently pursued in order to enable spectrum sharing—Shared Access Spectrum (SAS) and Licensed Spectrum Access (LSA).
The Spectrum Access System (SAS) allows for the implementation of an advanced three-tier spectrum sharing framework adopted for the Citizens Broadband Radio Service (CBRS) by the Federal Communications Commission (FCC) of the United States of America. The three-tiered sharing framework coordinates spectrum access among incumbents such as military communication facilities, priority access licensees (PALs) such as satellite earth stations and commercial users with General Authorized Access (GAA). The SAS is an advanced, highly automated radio spectrum coordinator within the CBRS 3.5 GHz band, and is tasked with protecting the higher-tier users from lower-tier users and optimizing efficient use of the available spectrum in the band for all users. As a result, the 150 MHz of CBRS spectrum is dynamically shared. The SAS maintains a database of all CBRS radio base stations including their tier status, geographical location, and other pertinent information to coordinate frequency and transmit power assignments, and to monitor and protect the band from potential interference.
Licensed Spectrum Access (LSA) facilitates access for additional licensees in bands which are already in use by one or more incumbents. LSA is a concept to dynamically share this band, whenever and wherever it is unused by the incumbent users. Shared use of the spectrum is only allowed on the basis of an individual authorisation (i.e. licensed). LSA is a further development of an industry proposal for Authorised Shared Access (ASA) concept, with the potential for application to other services in addition to mobile broadband, for example wireless cameras or the Internet of Things (IoT).
LSA is defined within the framework of the European Union as a regulatory approach aiming to facilitate the introduction of radio communication systems operated by a limited number of licensees under an individual licensing regime in a frequency band already assigned or expected to be assigned to one or more incumbent users. Under the Licensed Shared Access (LSA) approach, the additional users are authorised to use the spectrum (or part of the spectrum) in accordance with sharing rules included in their rights of use of spectrum, thereby allowing all the authorised users, including incumbents, to provide a certain Quality of Service (QoS).
Depending on the nature of the use of the band by the incumbent, the sharing rules can be fixed or there may be a need to use a repository which holds actual information on the use of specific frequencies in a given area by the incumbent. Based on this information an LSA or SAS controller can give clearance to the LSA/SAS user to use certain frequencies in the shared band. This means that if LSA/SAS is used in a mobile network, there might be a need to extend the network with functionality to control spectrum access by the base stations within the shared band. Since the mobile devices are under control of the base stations, there is no need to have any added functionality in the mobile devices.
For example, the Spectrum Monitoring and Detection Directorate (SMDD) of the Bangladesh Telecommunication Regulatory Commission (BTRC) has implemented an Automated Spectrum Management System (ASMS) which enables the SMDD to manage licensed assignments and to enable compliance monitoring in wireless communication networks (http://www.btrc.gov.bd/print/558).